<?php
// RSS 0.90  Officially obsoleted by 1.0
// RSS 0.91, 0.92, 0.93 and 0.94  Officially obsoleted by 2.0
// So, define constants for RSS 1.0, RSS 2.0 and ATOM

    define('RSS1', 'RSS 1.0', true);
    define('RSS2', 'RSS 2.0', true);
    define('ATOM', 'ATOM', true);

 /**
 * Univarsel Feed Writer class
 *
 * Genarate RSS 1.0, RSS2.0 and ATOM Feed
 *
 * @package     UnivarselFeedWriter
 * @author      Anis uddin Ahmad <anisniit@gmail.com>
 * @link        http://www.ajaxray.com/projects/rss
 */
 class FeedWriter
 {
     private $channels      = array();  // Collection of channel elements
     private $items         = array();  // Collection of items as object of FeedItem class.
     private $data          = array();  // Store some other version wise data
     private $CDATAEncoding = array();  // The tag names which have to encoded as CDATA

     private $version   = null;

    /**
    * Constructor
    *
    * @param    constant    the version constant (RSS1/RSS2/ATOM).
    */
    function __construct($version = RSS2)
    {
        $this->version = $version;

        // Setting default value for assential channel elements
        $this->channels['title']        = $version . ' Feed';
        $this->channels['link']         = 'http://www.ajaxray.com/blog';

        //Tag names to encode in CDATA
        $this->CDATAEncoding = array('description', 'content:encoded', 'summary');
    }

    // Start # public functions ---------------------------------------------

    /**
    * Set a channel element
    * @access   public
    * @param    srting  name of the channel tag
    * @param    string  content of the channel tag
    * @return   void
    */
    public function setChannelElement($elementName, $content)
    {
        $this->channels[$elementName] = $content ;
    }

    /**
    * Set multiple channel elements from an array. Array elements
    * should be 'channelName' => 'channelContent' format.
    *
    * @access   public
    * @param    array   array of channels
    * @return   void
    */
    public function setChannelElementsFromArray($elementArray)
    {
        if(! is_array($elementArray)) return;
        foreach ($elementArray as $elementName => $content)
        {
            $this->setChannelElement($elementName, $content);
        }
    }

    /**
    * Genarate the actual RSS/ATOM file
    *
    * @access   public
    * @return   void
    */
    public function genarateFeed()
    {
        header("Content-type: text/xml");

        $this->printHead();
        $this->printChannels();
        $this->printItems();
        $this->printTale();
    }

    /**
    * Create a new FeedItem.
    *
    * @access   public
    * @return   object  instance of FeedItem class
    */
    public function createNewItem()
    {
        $Item = new FeedItem($this->version);
        return $Item;
    }

    /**
    * Add a FeedItem to the main class
    *
    * @access   public
    * @param    object  instance of FeedItem class
    * @return   void
    */
    public function addItem($feedItem)
    {
        $this->items[] = $feedItem;
    }


    // Wrapper functions -------------------------------------------------------------------

    /**
    * Set the 'title' channel element
    *
    * @access   public
    * @param    srting  value of 'title' channel tag
    * @return   void
    */
    public function setTitle($title)
    {
        $this->setChannelElement('title', $title);
    }

    /**
    * Set the 'description' channel element
    *
    * @access   public
    * @param    srting  value of 'description' channel tag
    * @return   void
    */
    public function setDescription($desciption)
    {
        $this->setChannelElement('description', $desciption);
    }

    /**
    * Set the 'link' channel element
    *
    * @access   public
    * @param    srting  value of 'link' channel tag
    * @return   void
    */
    public function setLink($link)
    {
        $this->setChannelElement('link', $link);
    }

    /**
    * Set the 'image' channel element
    *
    * @access   public
    * @param    srting  title of image
    * @param    srting  link url of the imahe
    * @param    srting  path url of the image
    * @return   void
    */
    public function setImage($title, $link, $url)
    {
        $this->setChannelElement('image', array('title'=>$title, 'link'=>$link, 'url'=>$url));
    }

    /**
    * Set the 'about' channel element. Only for RSS 1.0
    *
    * @access   public
    * @param    srting  value of 'about' channel tag
    * @return   void
    */
    public function setChannelAbout($url)
    {
        $this->data['ChannelAbout'] = $url;
    }

  /**
  * Genarates an UUID
  * @author     Anis uddin Ahmad <admin@ajaxray.com>
  * @param      string  an optional prefix
  * @return     string  the formated uuid
  */
  public function uuid($key = null, $prefix = '')
  {
    $key = ($key == null)? uniqid(rand()) : $key;
    $chars = md5($key);
    $uuid  = substr($chars,0,8) . '-';
    $uuid .= substr($chars,8,4) . '-';
    $uuid .= substr($chars,12,4) . '-';
    $uuid .= substr($chars,16,4) . '-';
    $uuid .= substr($chars,20,12);

    return $prefix . $uuid;
  }
    // End # public functions ----------------------------------------------

    // Start # private functions ----------------------------------------------

    /**
    * Prints the xml and rss namespace
    *
    * @access   private
    * @return   void
    */
    private function printHead()
    {
        $out  = '<?xml version="1.0" encoding="utf-8"?>' . "\n";

        if($this->version == RSS2)
        {
            $out .= '<rss version="2.0"
                    xmlns:content="http://purl.org/rss/1.0/modules/content/"
                    xmlns:wfw="http://wellformedweb.org/CommentAPI/"
                  >' . PHP_EOL;
        }
        elseif($this->version == RSS1)
        {
            $out .= '<rdf:RDF
                     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
                     xmlns="http://purl.org/rss/1.0/"
                     xmlns:dc="http://purl.org/dc/elements/1.1/"
                    >' . PHP_EOL;;
        }
        else if($this->version == ATOM)
        {
            $out .= '<feed xmlns="http://www.w3.org/2005/Atom">' . PHP_EOL;;
        }
        echo $out;
    }

    /**
    * Closes the open tags at the end of file
    *
    * @access   private
    * @return   void
    */
    private function printTale()
    {
        if($this->version == RSS2)
        {
            echo '</channel>' . PHP_EOL . '</rss>';
        }
        elseif($this->version == RSS1)
        {
            echo '</rdf:RDF>';
        }
        else if($this->version == ATOM)
        {
            echo '</feed>';
        }

    }

    /**
    * Creates a single node as xml format
    *
    * @access   private
    * @param    srting  name of the tag
    * @param    mixed   tag value as string or array of nested tags in 'tagName' => 'tagValue' format
    * @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
    * @return   string  formatted xml tag
    */
    private function makeNode($tagName, $tagContent, $attributes = null)
    {
        $nodeText = '';
        $attrText = '';

        if(is_array($attributes))
        {
            foreach ($attributes as $key => $value)
            {
                $attrText .= " $key=\"$value\" ";
            }
        }

        if(is_array($tagContent) && $this->version == RSS1)
        {
            $attrText = ' rdf:parseType="Resource"';
        }


        $attrText .= (in_array($tagName, $this->CDATAEncoding) && $this->version == ATOM)? ' type="html" ' : '';
        $nodeText .= (in_array($tagName, $this->CDATAEncoding))? "<{$tagName}{$attrText}><![CDATA[" : "<{$tagName}{$attrText}>";

        if(is_array($tagContent))
        {
            foreach ($tagContent as $key => $value)
            {
                $nodeText .= $this->makeNode($key, $value);
            }
        }
        else
        {
            $nodeText .= (in_array($tagName, $this->CDATAEncoding))? $tagContent : htmlentities($tagContent);
        }

        $nodeText .= (in_array($tagName, $this->CDATAEncoding))? "]]></$tagName>" : "</$tagName>";

        return $nodeText . PHP_EOL;
    }

    /**
    * @desc     Print channels
    * @access   private
    * @return   void
    */
    private function printChannels()
    {
        //Start channel tag
        switch ($this->version)
        {
           case RSS2:
                echo '<channel>' . PHP_EOL;
                break;
           case RSS1:
                echo (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']}\">";
                break;
        }

        //Print Items of channel
        foreach ($this->channels as $key => $value)
        {
            if($this->version == ATOM && $key == 'link')
            {
                // ATOM prints link element as href attribute
                echo $this->makeNode($key,'',array('href'=>$value));
                //Add the id for ATOM
                echo $this->makeNode('id',$this->uuid($value,'urn:uuid:'));
            }
            else
            {
                echo $this->makeNode($key, $value);
            }

        }

        //RSS 1.0 have special tag <rdf:Seq> with channel
        if($this->version == RSS1)
        {
            echo "<items>" . PHP_EOL . "<rdf:Seq>" . PHP_EOL;
            foreach ($this->items as $item)
            {
                $thisItems = $item->getElements();
                echo "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . PHP_EOL;
            }
            echo "</rdf:Seq>" . PHP_EOL . "</items>" . PHP_EOL . "</channel>" . PHP_EOL;
        }
    }

    /**
    * Prints formatted feed items
    *
    * @access   private
    * @return   void
    */
    private function printItems()
    {
        foreach ($this->items as $item)
        {
            $thisItems = $item->getElements();

            //the argument is printed as rdf:about attribute of item in rss 1.0
            echo $this->startItem($thisItems['link']['content']);

            foreach ($thisItems as $feedItem )
            {
                echo $this->makeNode($feedItem['name'], $feedItem['content'], $feedItem['attributes']);
            }
            echo $this->endItem();
        }
    }

    /**
    * Make the starting tag of channels
    *
    * @access   private
    * @param    srting  The vale of about tag which is used for only RSS 1.0
    * @return   void
    */
    private function startItem($about = false)
    {
        if($this->version == RSS2)
        {
            echo '<item>' . PHP_EOL;
        }
        elseif($this->version == RSS1)
        {
            if($about)
            {
                echo "<item rdf:about=\"$about\">" . PHP_EOL;
            }
            else
            {
                die('link element is not set .\n It\'s required for RSS 1.0 to be used as about attribute of item');
            }
        }
        else if($this->version == ATOM)
        {
            echo "<entry>" . PHP_EOL;
        }
    }

    /**
    * Closes feed item tag
    *
    * @access   private
    * @return   void
    */
    private function endItem()
    {
        if($this->version == RSS2 || $this->version == RSS1)
        {
            echo '</item>' . PHP_EOL;
        }
        else if($this->version == ATOM)
        {
            echo "</entry>" . PHP_EOL;
        }
    }



    // End # private functions ----------------------------------------------

 } // end of class FeedWriter

 /**
 * Univarsel Feed Writer
 *
 * FeedItem class - Used as feed element in FeedWriter class
 *
 * @package         UnivarselFeedWriter
 * @author          Anis uddin Ahmad <anisniit@gmail.com>
 * @link            http://www.ajaxray.com/projects/rss
 */
 class FeedItem
 {
    private $elements = array();    //Collection of feed elements
    private $version;

    /**
    * Constructor
    *
    * @param    contant     (RSS1/RSS2/ATOM) RSS2 is default.
    */
    function __construct($version = RSS2)
    {
        $this->version = $version;
    }

    /**
    * Add an element to elements array
    *
    * @access   public
    * @param    srting  The tag name of an element
    * @param    srting  The content of tag
    * @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
    * @return   void
    */
    public function addElement($elementName, $content, $attributes = null)
    {
        $this->elements[$elementName]['name']       = $elementName;
        $this->elements[$elementName]['content']    = $content;
        $this->elements[$elementName]['attributes'] = $attributes;
    }

    /**
    * Set multiple feed elements from an array.
    * Elements which have attributes cannot be added by this method
    *
    * @access   public
    * @param    array   array of elements in 'tagName' => 'tagContent' format.
    * @return   void
    */
    public function addElementArray($elementArray)
    {
        if(! is_array($elementArray)) return;
        foreach ($elementArray as $elementName => $content)
        {
            $this->addElement($elementName, $content);
        }
    }

    /**
    * Return the collection of elements in this feed item
    *
    * @access   public
    * @return   array
    */
    public function getElements()
    {
        return $this->elements;
    }

    // Wrapper functions ------------------------------------------------------

    /**
    * Set the 'dscription' element of feed item
    *
    * @access   public
    * @param    string  The content of 'description' element
    * @return   void
    */
    public function setDescription($description)
    {
        $tag = ($this->version == ATOM)? 'summary' : 'description';
        $this->addElement($tag, $description);
    }

    /**
    * @desc     Set the 'title' element of feed item
    * @access   public
    * @param    string  The content of 'title' element
    * @return   void
    */
    public function setTitle($title)
    {
        $this->addElement('title', $title);
    }

    /**
    * Set the 'date' element of feed item
    *
    * @access   public
    * @param    string  The content of 'date' element
    * @return   void
    */
    public function setDate($date)
    {
        if(! is_numeric($date))
        {
            $date = strtotime($date);
        }

        if($this->version == ATOM)
        {
            $tag    = 'updated';
            $value  = date(DATE_ATOM, $date);
        }
        elseif($this->version == RSS2)
        {
            $tag    = 'pubDate';
            $value  = date(DATE_RSS, $date);
        }
        else
        {
            $tag    = 'dc:date';
            $value  = date("Y-m-d", $date);
        }

        $this->addElement($tag, $value);
    }

    /**
    * Set the 'link' element of feed item
    *
    * @access   public
    * @param    string  The content of 'link' element
    * @return   void
    */
    public function setLink($link)
    {
        if($this->version == RSS2 || $this->version == RSS1)
        {
            $this->addElement('link', $link);
        }
        else
        {
            $this->addElement('link','',array('href'=>$link));
            $this->addElement('id', FeedWriter::uuid($link,'urn:uuid:'));
        }

    }

    /**
    * Set the 'encloser' element of feed item
    * For RSS 2.0 only
    *
    * @access   public
    * @param    string  The url attribute of encloser tag
    * @param    string  The length attribute of encloser tag
    * @param    string  The type attribute of encloser tag
    * @return   void
    */
    public function setEncloser($url, $length, $type)
    {
        $attributes = array('url'=>$url, 'length'=>$length, 'type'=>$type);
        $this->addElement('enclosure','',$attributes);
    }

 }